Colonic leiomyomas are uncommon benign smooth muscle tumors that can mimic a more aggressive tumor on imaging, such as a GIST. They can be pedunculated, simulating a colonic polyp. Their characteristics are similar to leiomyomas in general.
Radiographic features
There are no specific findings on imaging, but they should appear similarly to leiomyomas elsewhere in the body.
If the leiomyoma is sessile:
- homogeneous soft-tissue attenuation on CT
- low signal intensity on T1 and T2 weighted imaging on MRI
- they should appear nonaggressive
- relatively smooth borders
- no invasion into adjacent structures
- no enlarged regional lymph nodes nor metastases
If the leiomyoma is polypoid, one will not be able to differentiate from other kinds of polyps.
Colonic leiomyomas are most often discovered at biopsy/polyp resection.
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